Can a Bad Battery Cause Slow Acceleration? (Detailed Explanation)

Can a Bad Battery Cause Slow Acceleration

A vehicle’s battery has various uses, including providing electrical current to start the engine. Besides, it powers several devices when the engine is off. Therefore, when it gets damaged, many car functions are affected.

But can a bad battery cause slow acceleration? The answer can be yes or no. If other vehicle parts of a gas-powered car are fine, the battery may not affect acceleration. However, faulty electrical parts may cause the engine to overwork. On the other hand, bad batteries in Hybrid and electric cars cause slow acceleration.

Still curious for more? Read on for a detailed explanation of how the battery affects these vehicles’ acceleration.

Can a Bad Battery Cause Slow Acceleration?

As previously said, the battery provides the engine with the first source of power used in starting the engine. Afterward, the vehicle depends on the engine and the alternator as the power source.

Now, what happens when the battery is bad? When the battery gets damaged, you may experience problems starting the car because the spark plug doesn’t receive enough current. In most cases, you’ll have to jump-start the engine to get it running.

However, as the vehicle is gas-powered, if the alternator supplies the required electrical current, acceleration may be unaffected. Also, modern vehicles disconnect power to the battery when accelerating to minimize power loss.

The battery also provides various car systems with electrical current, including the electronic fuel injection (EFI) system. When the engine is active, the alternator charges the battery and helps it power these systems.

But how does it affect acceleration? The following are ways the bad battery affects acceleration.

1. Alternator

When the battery is damaged, the alternator has to power all these systems, including the faulty battery, on its own. The diverted power can affect the engine’s performance and cause slow acceleration.

2. Systems Losing Power

The EFI and the spark plug are among the engine-related systems that depend on the electrical current. When the battery is damaged, these parts may get less power from the alternator and fail. When these parts fail, the engine may misfire and hesitate to accelerate.

3. CRDi Losing Power

Most modern diesel engines use a Common Rail Direct injection fuel system (CRDi,) which helps them meet emission control standards. Like the EFI, this system draws power from the battery and may fail if the current is low.

What Are the Symptoms of a Bad Car Battery?

Following are some symptoms of a bad car battery to help you determine whether your battery is faulty.

  • Troubles starting your vehicle
  • Corroded connectors
  • Accessories, like headlights, don’t get enough electrical current
  • Check engine light illuminating
  • Dashboard lights randomly illuminating
  • Strange odor when you open the hood
  • Poor mileage on hybrid cars

Does a Bad Battery Affect Acceleration on Hybrid Cars?

Since the discussion is about batteries in general and not specific on which types, it’s only fair to include motor car batteries. Hybrid vehicles combine an electric motor powered by batteries and a fuel engine to provide power to the engine.

Now, what happens when the battery goes bad? When the hybrid car’s motor battery breaks down, the acceleration is affected significantly. Because the vehicle is designed to alternate between fuel and the motor battery, depending on the gas alone will also affect its fuel economy.

The full hybrid cars are most affected by bad batteries, comparing the full, plug-in, and mild hybrid vehicles. Mainly, there is a high impact because the full hybrid heavily depends on the battery.

A hybrid vehicle also has a 12v battery which provides its electric current to power its electronic system. When this battery breaks down, just like in gas-powered cars, the acceleration is also affected.

Symptoms of a Bad Car Battery

Can a Bad Battery Cause Slow Acceleration on Electric Cars?

Unlike hybrid cars, electric cars fully depend on batteries to power their motors. Therefore, you’ll notice various symptoms if the battery goes bad, mostly at the end of its lifespan.

Slow acceleration is among these symptoms, which you can notice once the vehicle reaches certain speeds. Once the vehicle reaches around 40 mph, a reduced acceleration may point to a faulty motor battery. You can observe the vehicle’s battery health on the “my battery health app” on your smartphone.

Electric vehicles also have a 12V battery to power other accessories and systems. While the battery may have the least effect on acceleration, parts, like the sensors, may interfere with performance.

What Are the Solutions to Battery Problems Causing Slow Acceleration

The first step in solving battery problems is diagnosing the cause of its recent breakdowns. Loose connections and corroded poles are among the common causes, and the wiring might need a replacement.

However, if the 12-volt battery is the problem, it must be replaced with a new one. Depending on the batteries’ quality, a new one can cost between $70 and $250, labor costs included.

If your electric or hybrid car’s battery is faulty, buy a new one at your closest dealer. Replacing these batteries can cost anywhere between $3,800 and $22,000. However, sometimes individual cells may be faulty and should be replaced instead of the whole battery.

What Else Might Be Causing the Slow Acceleration?

If your vehicle has slow acceleration problems, but you doubt the battery is the cause, various things might be responsible. They include

  • A faulty spark plug

A failed spark plug may be causing a misfire in the engine resulting in a loss of power during acceleration.  Replace the spark plug to fix the problem.

  • Faulty Sensors

Various sensors in the throttle system may cause slow acceleration in a car. Hire a professional to check and replace them if they have issues.

  • Blocked air filters

The air filters purify the air flowing to the engine to remove dust, among other contaminants. If the filters get clogged, the engine may lack enough air needed affecting acceleration.

  • Dirty Fuel filters

The fuel filters clean the fuel going to the engine, and if dirty, it may restrict gas going to the engine. Clean or replace dirty fuel filters.

  • Exhaust System Problems

Whether it’s an exhaust leak or a clogged catalytic converter, exhaust system problems can cause slow acceleration. Diagnose and repair the failing parts.


A battery is a key part of a car, whether it’s fuel-powered, hybrid, or electric. Other than providing power to start the vehicle, it powers various accessories and systems. Also, as you know from the article, it affects the vehicle’s acceleration.

Before concluding to do the expensive battery repairs and replacements, observe for other symptoms that can confirm it’s faulty. Also, check for other possible causes of the slow accelerations as they may be the cause and not the battery.

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